This disclosure relates to a large press for forming thin walled hollow drawn containers from precoated stock by a series of multiple forming operations in the press. More particularly, a press is disclosed which can put out about 700 containers per minute. The containers being formed by the operations of blanking and cupping, drawing, redrawing-profiling and trimming. In the past there has been a unitary press for producing such hollow drawn containers at rates of about 125 per minute. This press is disclosed in, for example, U.S. Pat. No. 4,262,510. Such a press was limited in terms of capacity by the nature of its mechanical design for handling the containers and the material entering and leaving the press. In addition, there have been arrangements for producing such containers in a more efficient manner by using multiple presses with transfer conveyors between them. Those arrangements require synchronization between the multiple presses and take more space and money to construct and operate. Consequently, the need for at least two presses in such a system subjects one press to the infirmities of its companion. That is to say that, if one or the other is down both are down. Similarly, difficulty with the conveyor will stop production.
The container made by the press disclosed herein is best disclosed in connection with U.S. Ser. No. 234,452 CONTAINER, wherein a detailed description of the type of container and its construction and use are provided. Such containers must be made on high speed equipment as their cost must be minimized for each is a disposable single use item. Similarly, such containers are usually made of precoated stock as disclosed, for instance, in U.S. Ser. No. 230,610, DRAWABLE COATING. It, therefore, becomes important to make and handle the containers at high speeds but with sufficient care to prevent damage to the thin wall or fragile precoating during the multiple forming operations.
In the past, techniques have been suggested for moving partially formed containers through the tooling in a press for progressive forming, see, for example, U.S. Pat. No. 4,373,370 PRESS TRANSFER BAR or more germaine to this particular disclosure, U.S. Pat. No. Re. 29,645 which discloses a transfer arrangement which does not provide positive displacement or handling of the containers during transfer from one operating station to the next. U.S. Pat. No. 1,935,854 discloses an intermittent transfer operation akin to that of the present disclosure but not as uniform or continuous. Here the mechanism for transferring the partially formed drawn and redrawn containers have been streamlined so that a gang of such transfer mechanisms can be included within the press opening between the tools.
It is also important that a press capable of manufacturing containers at the speeds required be simple and compact. In a large press a series of refinements in every area of the press construction promote structural integrity and operational efficiency. More particularly, it is essential that the operations which require large tools and large space be done on one side of the press crown and those operations that can be closer together be done on another side of the press crown such that the overall size of the press in plan is minimized. U.S. Pat. No. 4,026,226 shows an inverted press with forming operations above and below the crown such that distinct operations can be made separately in the same press. In that press, tabs are made atop the crown and ends are made beneath the crown. The tabs are assembled to the ends beneath the crown. That press merely separates the tooling but not for economy of space or construction and also not to minimize the horsepower required to drive the press. More specifically, the peak load requirements are cut by using both the upstroke and downstroke of the press and, in addition, the load on the driving members is balanced better.
In order to be able to do multiple operations at different levels in the same press handling of the containers becomes critical. Handling techniques, equipment and processes have been disclosed in connection with the aforementioned inverted presses. More particularly, in the end press the tab is carried by the parent metal from which it is formed to the opposite side of the crown for assembly to the end. In the prior inverted container press, the partially formed cans are transferred by oscillating fingers carried by shifting transfer bars. With those arrangements piece part movement during progressive forming is accurate but the mechanisms are large and complicated. A simple mechanism for multi-lane transfer in a large progressive press has not been seen in the prior art.
To minimize the overall size of such large presses for multiple forming containers at high speeds, it is necessary to drive more than one portion of the tooling off of one portion of the crank shaft using a common drive element thus minimizing the number of connecting rods, drive arms and the like. To some extent this feature has been disclosed in the aforementioned inverted end press, however, in a large press with multiple forming stations above and below the crown this feature has been significantly refined. Furthermore, the clamping and forming rams have been nested aside one another rather than being stacked atop of one another, or as in the past, nested by placing one ram in the hollow confines of another and gibbing the first to the second such that the tolerances of the nested ram and those of the carrying ram in which it is nested are cumulative. Here the gibbing systems are independent of one another such that tolerance problems are minimized. In addition, gibbing systems have usually had external or open lubrication subject to environmental conditions and dirt thus causing a certain amount of mess in the press where the products are made as well as in the surrounding environment of the plant. This open lubrication of the gibbing causes problems of cleanliness, loss of lubricant and requires particular care in making good sanitary food containers. Similarly, the use of cushion cylinders which get within the same and about the tooling in order to maintain a minimum overall height is unique. In the crank case for the press there is a worm and gear drive. The roller bearings for the worm are set in the sides of the crank case such that lubricant for the bearings is pumped into them from above and removed from below. This arrangement to be effective must control the flow of oil through the bearings to prevent churning which would cause oil degradation and overheating. Vertical press size limitations, crankcase wall strength and requisite support for the bearing prevent the use of sufficiently large passages to provide adequate flow for draining these bearings.
Every press frame is constructed from a series of individual components. The components are usually fashioned in accordance with the facilities available for manufacturing the press frame parts and in accordance with the need to maintain tolerances as required for the accuracy necessary to make the press assembly and operate efficiently and reliably. Nowhere is there disclosed a press that is composed of multiple subassemblies which are individually operative units for run-in or testing purposes, but which interconnect to permit the various subassemblies to cooperate with each other. Furthermore, the opportunity to individually check such subassemblies of a large press prior to assembly of the whole or during repair of one portion are not disclosed in any of the art.